Demo - jquery-change-textbox-value-based-on-dropdown-selection

Edit This Code :

<html>
<head><script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
</head>
<body>

<input type="textbox" id="myTextbox" />
<select id="ddlModel">
<option value="">--Select--</option>
<option value="Iphone">Iphone</option>
<option value="Samsung">Samsung</option>
<option value="Sony">Sony</option>
<option value="Vivo">Vivo</option>
</select>

<script>
$(document).ready(function(){
	
$("#ddlModel").on("change",function(){
   var GetValue=$("#ddlModel").val();
   $("#myTextbox").val(GetValue);
});

});

</script>
</body>
</html>

Result :